Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 E-mail Us
 Oracle Articles
New Oracle Articles

 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog

 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Oracle Support

 SQL Tuning

 Oracle UNIX
 Oracle Linux
 Remote s
 Remote plans
 Application Server

 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S


 Consulting Staff
 Consulting Prices
 Help Wanted!


 Oracle Posters
 Oracle Books

 Oracle Scripts

Don Burleson Blog 







ASSM bitmap freelists

Oracle Database Tips by Donald Burleson

Oracle Grid Computing with RAC

Automatic Segment Space Management

When an object such as a table or index is created using the locally managed tablespace, with automatic segment-space management enabled, there is no need to specify the pctfree or freelists.

The in-segment free/used space is tracked using bitmaps as opposed to the free lists. When you cannot use the locally managed tablespace, and therefore the automatic management space feature, you have to depend on the traditional method of managing free lists and free lists groups. We will cover the free list method of RAC in a later part of this section.

Automatic segment-space management offers the following benefits:

  • It provides administrative ease of use by avoiding the specification of storage parameters.

  • It is a good method for handling objects with varying row sizes.

  • It provides better run-time adjustment for variations in concurrent access and avoids tedious tuning methods.

  • It provides better multi-instance behavior in terms of performance/space utilization.

However, note that this automatic feature of segment space management is available only with locally managed tablespaces and their objects. A new column called SEGMENT_SPACE_MANAGEMENT AUTO has been added to the dba_tablespaces view to indicate the segment space management mode used by a tablespace.

The above text is an excerpt from:

Oracle 10g Grid & Real Application Clusters
Oracle 10g Grid Computing with RAC
ISBN 0-9744355-4-6

by Mike Ault, Madhu Tumma


Oracle Training at Sea
oracle dba poster

Follow us on Twitter 
Oracle performance tuning software 
Oracle Linux poster


Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

and include the URL for the page.


Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


Copyright © 1996 -  2020

All rights reserved by Burleson

Oracle ® is the registered trademark of Oracle Corporation.